Ground-dwelling Arthropod Communities Research Articles

Ground-Dwelling Arthropod Community Responses to Recent and Repeated Wildfires in Conifer Forests of Northern New Mexico, USA

The increasing frequency and severity of wildfires in semi-arid conifer forests as a result of global change pressures has raised concern over potential impacts on biodiversity. Ground-dwelling arthropod communities represent a substantial portion of diversity in conifer forests, and could be particularly impacted by wildfires. In addition to direct mortality, wildfires can affect ground-dwelling arthropods by altering understory characteristics and associated deterministic community assembly processes (e.g., environmental sorting). Alternatively, disturbances have been reported to increase the importance of stochastic community assembly processes (e.g., probabilistic dispersal and colonization rates). Utilizing pitfall traps to capture ground-dwelling arthropods within forest stands that were burned by one or two wildfires since 1996 in the Jemez Mountains of northern New Mexico, United States (USA), we examined the potential influences of deterministic versus stochastic processes on the assembly of these diverse understory communities. Based on family-level and genera-level arthropod identifications, we found that the multivariate community structures differed among the four fire groups surveyed, and were significantly influenced by the quantities of duff, litter, and coarse woody debris, in addition to tree basal area and graminoid cover. Taxon diversity was positively related to duff quantities, while taxon turnover was positively linked to exposed-rock cover and the number of logs on the ground. Despite the significant effects of these understory properties on the arthropod community structure, a combination of null modeling and metacommunity analysis revealed that both deterministic and stochastic processes shape the ground-dwelling arthropod communities in this system. However, the relative influence of these processes as a function of time since the wildfires or the number of recent wildfires was not generalizable across the fire groups. Given that different assembly processes shaped arthropod communities among locations that had experienced similar disturbances over time, increased efforts to understand the processes governing arthropod community assembly following disturbance is required in this wildfire-prone landscape.

Ground-Dwelling Arthropod Community Response to Livestock Grazing: Implications for Avian Conservation.

Terrestrial arthropods are a critical component of rangeland ecosystems that convert primary production into resources for higher trophic levels. During spring and summer, select arthropod taxa are the primary food of breeding prairie birds, of which many are imperiled in North America. Livestock grazing is globally the most widespread rangeland use and can affect arthropod communities directly or indirectly through herbivory. To examine effects of management on arthropod community structure and avian food availability, we studied ground-dwelling arthropods on grazed and ungrazed sagebrush rangelands of central Montana. From 2012 to 2015, samples were taken from lands managed as part of a rest-rotation grazing program and from idle lands where livestock grazing has been absent for over a decade. Bird-food arthropods were twice as prevalent in managed pastures despite the doubling of overall activity-density of arthropods in idle pastures. Activity-density on idled lands was largely driven by a tripling of detritivores and a doubling in predators. Predator community structure was simplified on idled lands, where Lycosid spiders increased by fivefold. In contrast, managed lands supported a more diverse assemblage of ground-dwelling arthropods, which may be particularly beneficial for birds in these landscapes if, for example, diversity promotes temporal stability in this critical food resource. Our results suggest that periodic disturbance may enhance arthropod diversity, and that birds may benefit from livestock grazing with periodic rest or deferment.

Cascading effects of mammalian herbivores on ground-dwelling arthropods: Variable responses across arthropod groups, habitats and years.

Large mammalian herbivores are well known to shape the structure and function of ecosystems world-wide, and these effects can in turn cascade through systems to indirectly influence other animal species. A wealth of studies has explored the effects of large mammals on arthropods, but to date they have reported such widely varying results that generalizations have been elusive. Three factors are likely drivers of this variability: the widely varying life-history characteristics of different arthropod groups, the highly variable landscapes that mammalian herbivores commonly inhabit and temporal variation in environmental conditions. Here, we use an 18-year-old exclosure experiment stratified across three distinct coastal prairie habitats in northern California to address the effects of a reintroduced mammalian herbivore, tule elk (Cervus canadensis nannodes) on the composition, richness and abundance of ground-dwelling arthropods over two years with very different precipitation regimes. We found that elk shifted the composition of arthropod communities, increasing the abundance of ants, beetles, spiders and mites, decreasing the abundance of woodlice and bristletails in some but not all habitats types, and having no effect on the abundance of bugs, crickets and springtails. Elk also increased richness and changed the composition of ant genera and beetle morpho-species. Interestingly, the effects of elk on arthropod composition, richness and abundance varied little between years, despite very different precipitation levels, biomass accumulation and thatch height. Elk reduced shrub cover, above-ground herbaceous biomass and thatch height and increased soil compaction, and these changes predicted the abundance and richness of arthropods, although taxonomic groups varied in their responses, presumably due to differences in environmental requirements. Synthesis. Our research highlights the importance of using long-term experiments to assess the cascading effects of large herbivores on the composition of grounddwelling arthropod communities and to identify the mechanisms that indirectly shape arthropod responses to herbivores among variable habitats and years in order to develop a greater understanding of the variable responses of arthropods to large mammalian herbivores.

Cover Crop Species and Management Influence Predatory Arthropods and Predation in an Organically Managed, Reduced-Tillage Cropping System.

Agricultural practices affect arthropod communities and, therefore, have the potential to influence the activities of arthropods. We evaluated the effect of cover crop species and termination timing on the activity of ground-dwelling predatory arthropods in a corn-soybean-wheat rotation in transition to organic production in Pennsylvania, United States. We compared two cover crop treatments: 1) hairy vetch (Vicia villosa Roth) planted together with triticale (×Triticosecale Wittmack) after wheat harvest, and 2) cereal rye (Secale cereale Linnaeus) planted after corn harvest. We terminated the cover crops in the spring with a roller-crimper on three dates (early, middle, and late) based on cover crop phenology and standard practices for cash crop planting in our area. We characterized the ground-dwelling arthropod community using pitfall traps and assessed relative predation using sentinel assays with live greater waxworm larvae (Galleria mellonella Fabricius). The activity density of predatory arthropods was significantly higher in the hairy vetch and triticale treatments than in cereal rye treatments. Hairy vetch and triticale favored the predator groups Araneae, Opiliones, Staphylinidae, and Carabidae. Specific taxa were associated with cover crop condition (e.g., live or dead) and termination dates. Certain variables were positively or negatively associated with the relative predation on sentinel prey, depending on cover crop treatment and stage, including the presence of predatory arthropods and various habitat measurements. Our results suggest that management of a cover crop by roller-crimper at specific times in the growing season affects predator activity density and community composition. Terminating cover crops with a roller-crimper can conserve generalist predators.

耕作方式对玉-豆轮作地表节肢动物多样性及其营养结构的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 耕作方式对玉-豆轮作地表节肢动物多样性及其营养结构的影响 DOI: 10.5846/stxb201709221712 作者: 作者单位: 中国科学院东北地理与农业生态研究所,吉林大学;吉林大学,商丘师范学院,中国科学院东北地理与农业生态研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41501263，41430857）；中国博士后科学基金面上项目（2016M590269）；河南省科技厅科技攻关项目（172102410054）；商丘师范学院骨干教师项目（2015GGJS15）；2014年河南省哲学社会科学规划项目（2014CJJ087） Response of ground-dwelling arthropod community diversity and its trophic structure in relation tillage regimes under maize-soybean rotation Author: Affiliation: College of Surveying and Planning,Shangqiu Normal University,,,Northeast Institute of Geography and Agroecology Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为阐明长期不同耕作方式对轮作种植模式黑土农田地表节肢动物多样性及其营养结构的影响，2015年5月至9月间，利用陷阱法对连续13年玉米大豆轮作模式的定位试验站三种耕作方式（免耕、垄作、秋翻）的地表节肢动物群落进行了调查。共捕获动物1002只，隶属于3纲11目29科37个类群，凹唇蚁、玉米毛蚁和直角通缘步甲为优势类群。免耕（NT，no tillage）有利于增加蜘蛛类群密度，垄作（RT，ridge tillage）和秋翻（MP，mould board plough）显著增加了玉米毛蚁密度。耕作方式仅对群落密度有显著影响显著影响（P < 0.05），而大豆不同生育阶段显著或极显著的影响地表节肢动物群落组成特征（P < 0.05；P < 0.001）。长期玉米大豆轮作种植的地表节肢动物群落营养功能群在不同耕作方式中所占比例不同，保护性耕作方式（NT、RT）更有利于捕食性和植食性动物的生存和繁殖，常规耕作（MP）则是杂食性动物占据优势，明显呈现对不稳定环境的适应。大豆不同生育期，各功能群的个体数与类群数的动态变化不尽一致，不具有明显的规律性。研究结果表明，免耕轮作对维持地表节肢动物群落内部物种间的关系及其营养结构有着较为重要的作用，保护性耕作和轮作种植模式相结合可维持农田生态系统平衡。 Abstract:Conservation tillage, such as reduced tillage or no-tillage, may play an important role in increasing soil organic matter, reducing soil erosion, and providing a more complex and favorable habitat for soil-dwelling organisms. Aboveground arthropods are important components of ecosystems, promoting a number of key functions, such as decomposition of organic matter and some herbivorous pest control. The abundance and diversity of food web components depends highly on the rotation system and soil management. To reveal the effect of tillage regimes on the diversity and trophic structure of ground-dwelling arthropods under maize-soybean rotation in the black soil of Northeast China, five field investigations were conducted with three tillage regimes (no tillage, NT; ridge tillage, RT; mould board plough, MP) at a 13-year tillage regime experiment station. A total of 1002 arthropod individuals belonging to 3 classes, 11 orders, 29 families, and 37 groups were collected. Formica sanguinea Letreille, Lasius alienus Foerster, and Poecilus gebleri Dejean were the dominant species and accounted for 60.58% of the total individuals. The results showed that NT was beneficial to the spider population resulting in increased densities, and RT and MP significantly increased the density of Lasius alienus. Tillage regimes only significantly affected the density of arthropod communities in different growth stages (P < 0.05), whereas different growth stages of soybeans significantly or highly significantly affected the density, groups, and diversity of the arthropod community under different tillage regimes (P < 0.05; P < 0.001). In the long-term, under the maize and soybean rotation system, the proportion of trophic functional groups was different under the different tillage practices. The results indicated that the long-term conservation tillage (NT and RT) was more conducive to the survival of predators and herbivorous arthropods. Omnivores were dominant in the MP system, showing obvious adaptation to the unstable environment. In the different growth stages of the soybeans, the variation in all functional groups was not consistent, and there was no obvious pattern. It is obvious that no-tillage with rotation play an important role in maintaining the relationship between the species within the community and the trophic structure of the food web. 参考文献 相似文献 引证文献

Community structure of grassland ground-dwelling arthropods along increasing soil salinities.

Ground-dwelling arthropod communities are influenced by numerous biotic and abiotic factors. Little is known, however, about the relative importance of vegetation structure and abiotic environmental factors on the patterns of ground-dwelling arthropod community across a wide range of soil salinities. Here, a field survey was conducted to assess the driving forces controlling ground-dwelling arthropod community in the salinized grasslands in the Hexi Corridor, Gansu Province, China. The data were analyzed by variance partitioning with canonical correspondence analysis (CCA). We found that vegetation structure and edaphic factors were at least of similar importance to the pattern of the whole ground-dwelling arthropod community. However, when all collected ground-dwelling arthropods were categorized into three trophic guilds (predators, herbivores, and decomposers), as these groups use different food sources, their populations were controlled by different driving forces. Predators and decomposers were mainly determined by biotic factors such as vegetation cover and aboveground plant biomass and herbivores by plant density and vegetation cover. Abiotic factors were also major determinants for the variation occurring in these guilds, with predators strongly affected by soil electrical conductivity (EC) and the content of fine particles (silt + clay, CS), herbivores by soil N:P, EC, and CS, and decomposers by soil EC and organic matter content (SOM). Since plant cover, density, and aboveground biomass can indicate resource availability, which are mainly constrained by soil N:P, EC, CS, and SOM, we consider that the ground-dwelling arthropod community in the salinized grasslands was mainly influenced by resource availability.

Impacts of management intensification on ground-dwelling beetles and spiders in semi-natural mountain grasslands

Agricultural intensification is one of the major threats to the biodiversity of montane and subalpine grasslands. This calls for regional agriculture policies that efficiently protect their flora and fauna without jeopardizing agricultural viability. We experimentally sought a sustainable management, testing the effects of fertilisation (slurry) and aerial irrigation (sprinklers) – separately and in combination (at different levels of intensity) – on the arthropod communities occurring in extensively-managed montane and subalpine meadows in the SW Swiss Alps. Four years after the start of the intensification experiment, we measured the abundance, species richness, community composition and variability (β-diversity) of ground-dwelling beetles and spiders. The abundance of both taxa showed a curvilinear relationship with management intensity. Spider abundance peaked at a moderate level of intensification while ground beetle abundance appeared to be more resilient to intensification, peaking at a high level of intensification. These responses were mainly driven by fertilisation, while irrigation played a minor role. For both taxa, we found no impact of irrigation or fertilisation, either when applied separately or in combination on species richness. Community composition was altered by management intensification in both taxa, but community variability was not. Given these taxon-specific patterns for abundance, applying organic fertiliser and water at levels corresponding to two-thirds of the quantity necessary to achieve local maximum hay yield appears to be compatible with the maintenance of rich ground-dwelling arthropod communities in mountain grasslands.

Characterizing Movement of Ground-Dwelling Arthropods with a Novel Mark-Capture Method Using Fluorescent Powder

A major knowledge gap exists in understanding dispersal potential of ground-dwelling arthropods, especially in forest ecosystems. Movement of the ground-dwelling arthropod community was quantified using a novel mark-capture technique in which three different colored fluorescent powders in two separate mixtures were applied to the floor of a deciduous forest in concentric bands 3, 8, and 15 m from the center of 30 × 30 m experimental plots. The majority (67.1%) of ground-dwelling arthropods did not cross a colored band when fluorescents were mixed with protein powder in 2014. However, when mixed with sand in 2015, 77.3% of captured arthropods were marked with fluorescent powder, with the majority of individuals crossing one band (41.2%), suggesting limited dispersal by most individuals in the community. Only 2.8% and 15.0% of arthropods crossed all three bands in 2014 and 2015, respectively, which further indicates that individuals have limited dispersal. Responses were taxon-specific, and a high proportion of some arthropods such as millipedes and harvestmen crossed two or three bands. Limited dispersal by most individuals may have important implications for the structure and distribution of ground-dwelling arthropod communities, as well as their responses to natural or anthropogenic disturbances. Our results demonstrate the feasibility of this novel technique for self-marking and capturing individuals in the field to investigate dispersal of ground-dwelling arthropods.

Aboveground and belowground arthropods experience different relative influences of stochastic versus deterministic community assembly processes following disturbance.

BackgroundUnderstanding patterns of biodiversity is a longstanding challenge in ecology. Similar to other biotic groups, arthropod community structure can be shaped by deterministic and stochastic processes, with limited understanding of what moderates the relative influence of these processes. Disturbances have been noted to alter the relative influence of deterministic and stochastic processes on community assembly in various study systems, implicating ecological disturbances as a potential moderator of these forces.MethodsUsing a disturbance gradient along a 5-year chronosequence of insect-induced tree mortality in a subalpine forest of the southern Rocky Mountains, Colorado, USA, we examined changes in community structure and relative influences of deterministic and stochastic processes in the assembly of aboveground (surface and litter-active species) and belowground (species active in organic and mineral soil layers) arthropod communities. Arthropods were sampled for all years of the chronosequence via pitfall traps (aboveground community) and modified Winkler funnels (belowground community) and sorted to morphospecies. Community structure of both communities were assessed via comparisons of morphospecies abundance, diversity, and composition. Assembly processes were inferred from a mixture of linear models and matrix correlations testing for community associations with environmental properties, and from null-deviation models comparing observed vs. expected levels of species turnover (Beta diversity) among samples.ResultsTree mortality altered community structure in both aboveground and belowground arthropod communities, but null models suggested that aboveground communities experienced greater relative influences of deterministic processes, while the relative influence of stochastic processes increased for belowground communities. Additionally, Mantel tests and linear regression models revealed significant associations between the aboveground arthropod communities and vegetation and soil properties, but no significant association among belowground arthropod communities and environmental factors.DiscussionOur results suggest context-dependent influences of stochastic and deterministic community assembly processes across different fractions of a spatially co-occurring ground-dwelling arthropod community following disturbance. This variation in assembly may be linked to contrasting ecological strategies and dispersal rates within above- and below-ground communities. Our findings add to a growing body of evidence indicating concurrent influences of stochastic and deterministic processes in community assembly, and highlight the need to consider potential variation across different fractions of biotic communities when testing community ecology theory and considering conservation strategies.

Spinosad and spinetoram disrupt the structure and the abundance of ground-dwelling arthropod communities in herbaceous fields

ABSTRACTIn the present study, the effects of spinosad, spinetoram and chlorpyrifos on ground-dwelling arthropod diversity and abundance were compared in a herbaceous field in order to evaluate their relative compatibility with conservation of arthropod densities. Ten different treatments of spinosad, spinetoram, and chlorpyrifos, which was used as a toxic reference, were allocated at random to experimental plots. A total of 101,119 individuals of epigeal arthropods belonging to 18 orders and suborders were captured in pitfall traps, with the most abundant taxa Hymenoptera, Collembola, Araneae, Acari, Coleoptera, Isopoda, Julida and Opiliones. The orders Araneae, Coleoptera, Collembola, Hymenoptera and Opiliones were identified to the family or species level. Gnaphosidae, Carabidae, Entomobryidae, Formicidae and Metaplatybunus grandissimus CL Koch (Phalangiidae) were the most abundant taxa of Araneae, Coleoptera, Collembola, Hymenoptera and Opiliones, respectively. Significant density reduction was observed for Gnaphosidae, Linyphiidae (Araneae), Carabidae, Entomobryidae, Formicidae and M. grandissimus after chlorpyrifos treatment. Formicidae individuals were significantly reduced after spinosad application, while the Entomobryidae and M. grandissimus individuals were reduced after the application of both spinosad and spinetoram. Our results showed no significant differences in diversity level of orders and suborders as well as of Araneae families between the spinetoram-treated plots at both concentrations tested and the control. In contrast, a significant difference in the diversity of Coleoptera was detected between the spinetoram treatments and the control. Our findings showed that spinosad and spinetoram may disrupt the structure and the abundance of surface-active arthropod fauna causing considerable changes in the ground-dwelling biodiversity of this ecosystem.

Biodiversity effects and rates of spread of nonnative eucalypt woodlands in central California

Woodlands comprised of planted, nonnative trees are increasing in extent globally, while native woodlands continue to decline due to human activities. The ecological impacts of planted woodlands may include changes to the communities of understory plants and animals found among these nonnative trees relative to native woodlands, as well as invasion of adjacent habitat areas through spread beyond the originally planted areas. Eucalypts (Eucalyptus spp.) are among the most widely planted trees worldwide, and are very common in California, USA. The goals of our investigation were to compare the biological communities of nonnative eucalypt woodlands to native oak woodlands in coastal central California, and to examine whether planted eucalypt groves have increased in size over the past decades. We assessed site and habitat attributes and characterized biological communities using understory plant, ground-dwelling arthropod, amphibian, and bird communities as indicators. Degree of difference between native and nonnative woodlands depended on the indicator used. Eucalypts had significantly greater canopy height and cover, and significantly lower cover by perennial plants and species richness of arthropods than oaks. Community composition of arthropods also differed significantly between eucalypts and oaks. Eucalypts had marginally significantly deeper litter depth, lower abundance of native plants with ranges limited to western North America, and lower abundance of amphibians. In contrast to these differences, eucalypt and oak groves had very similar bird community composition, species richness, and abundance. We found no evidence of "invasional meltdown," documenting similar abundance and richness of nonnatives in eucalypt vs. oak woodlands. Our time-series analysis revealed that planted eucalypt groves increased 271% in size, on average, over six decades, invading adjacent areas. Our results inform science-based management of California woodlands, revealing that while bird communities would probably not be affected by restoration of eucalypt to oak woodlands, such a restoration project would not only stop the spread of eucalypts into adjacent habitats but would also enhance cover by western North American native plants and perennials, enhance amphibian abundance, and increase arthropod richness.

Moss invasion in a dune ecosystem influences ground-dwelling arthropod community structure and reduces soil biological activity

One of the most invasive moss species worldwide is Campylopus introflexus, which can change vegetation and habitat conditions of native ecosystems (dunes, heathland). However, the impact of the moss on the community structure of multiple arthropod taxa and ecosystem functions is still poorly understood. For a better understanding of impacts of invasive species, scientific studies are needed which explicitly define the investigated impact. We defined impact based on the most recently recommended categories: ‘directionality’, ‘classification and measurement’, ‘ecological or socio-economic changes’, and ‘scale’. We investigated the impact of C. introflexus on a wide range of ground-dwelling arthropods (pitfall traps) and on soil biological activity (bait-lamina test) by comparing invaded and uninvaded grey dunes in a field observational study on the island of Hiddensee, Germany. We found that the moss and the associated habitat modifications influenced the arthropod community structure. The effects on arthropod densities were taxon-specific and were positive (Coleoptera, Formicidae, Opiliones) or neutral (Araneae, Orthoptera). For Collembola and Isopoda we assumed an indirectly negative effect of the moss due to associated lower field layer cover and soil moisture. C. introflexus drastically reduced the soil biological activity, which was about six times lower in invaded grey dunes. The reduced soil moisture associated with the moss invasion was identified as the main driver of the shifts in community structure and soil biological activity. By explicitly defining ‘impact’ in our study, we add to recent discussions within invasion ecology about invasive species impacts. Our study demonstrates the importance of cross-taxon approaches which include key ecosystem processes such as soil biological activity and therefore contributes to the progress towards the general understanding of plant invasion impacts.

Ground-Dwelling Arthropod Communities of a Sky Island Mountain Range in Southeastern Arizona, USA: Obtaining a Baseline for Assessing the Effects of Climate Change.

The few studies that have addressed past effects of climate change on species distributions have mostly focused on plants due to the rarity of historical faunal baselines. However, hyperdiverse groups like Arthropoda are vital to monitor in order to understand climate change impacts on biodiversity. This is the first investigation of ground-dwelling arthropod (GDA) assemblages along the full elevation gradient of a mountain range in the Madrean Sky Island Region, establishing a baseline for monitoring future changes in GDA biodiversity. To determine how GDA assemblages relate to elevation, season, abiotic variables, and corresponding biomes, GDA were collected for two weeks in both spring (May) and summer (September) 2011 in the Santa Catalina Mountains, Arizona, using pitfall traps at 66 sites in six distinct upland (non-riparian/non-wet canyon) biomes. Four arthropod taxa: (1) beetles (Coleoptera), (2) spiders (Araneae), (3) grasshoppers and crickets (Orthoptera), and (4) millipedes and centipedes (Myriapoda) were assessed together and separately to determine if there are similar patterns across taxonomic groups. We collected 335 species of GDA: 192/3793 (species/specimens) Coleoptera, 102/1329 Araneae, 25/523 Orthoptera, and 16/697 Myriapoda. GDA assemblages differed among all biomes and between seasons. Fifty-three percent (178 species) and 76% (254 species) of all GDA species were found in only one biome and during only one season, respectively. While composition of arthropod assemblages is tied to biome and season, individual groups do not show fully concordant patterns. Seventeen percent of the GDA species occurred only in the two highest-elevation biomes (Pine and Mixed Conifer Forests). Because these high elevation biomes are most threatened by climate change and they harbor a large percentage of unique arthropod species (11–25% depending on taxon), significant loss in arthropod diversity is likely in the Santa Catalina Mountains and other isolated mountain ranges in the Southwestern US.

Ground-Dwelling Arthropod Communities Related to Nesting Success of Northern Bobwhite at Two Western Oklahoma Wildlife Management Areas

Abstract. Numbers of northern bobwhite, Colinus virginianus (L.), have decreased during the past 50 years in Oklahoma. It is unknown if the availability of grounddwelling arthropods on which bobwhite chicks rely for 80% of their protein requirements plays a role because little is known of ground-dwelling arthropod communities in bobwhite habitats of western Oklahoma. We used pitfall traps to sample community composition and size classes of ground-dwelling arthropods along transects that spanned four vegetation zones at two wildlife management areas occupied by bobwhites in western Oklahoma and recorded the abundance of quail nests per zone. After collecting and identifying 58,020 arthropods from families known to be eaten by quail, we found 60% of the arthropods ideally suited for quail consumption were in riparian zones, and that most quail nested in upland zones. Approximately 15% of nests were in the zones with the most abundant arthropods in the Packsaddle Wildlife Management Area during 2013, compare...

Changes in ground-dwelling arthropod diversity related to the proximity of shrub cover in a desertified system

Shrub patchiness generates spatial heterogeneity across a range of scales. Little is known about shrub-patch effects on ground-dwelling arthropod diversity on small spatial scales. Using pitfall trapping, ground-dwelling arthropods were collected at three microsites (beneath and on the shrub-canopy periphery, and in open spaces) during spring, summer, and autumn, in a desertified steppe ecosystem of northwestern China. Along with distance from shrub cover, the abundance of dominant groups, including Carabidae, Tenebrionidae, and Glaphyridae families, tended to decrease and was remarkably affected by seasonality, in contrast to the abundance distribution pattern of the dominant Melolonthidae, Curculionidae, and Formicidae families. The distribution pattern of total abundance, group richness, and Fisher's α index among the microsites was also found to be affected by seasonality. Together, the abundance distribution of different dominant taxa was found to indicate distinctive responses to the microsite and seasonal variability. The distribution pattern of the ground-dwelling arthropod community among the microsites could change along with seasonality, though high diversity was found to be maintained beneath the shrub cover. This study elucidated the importance of plant-cover functions as ‘keystone structures’, providing heterogeneous microsite – soil arthropod relationships that altered in time and space in xeric environments.

Cover crop and tillage intensities alter ground-dwelling arthropod communities during the transition to organic production

AbstractWe conducted a cropping systems experiment in central Pennsylvania, USA, to determine the effects of initial cover crop species and soil management on the abundance and composition of the ground-dwelling arthropod community. We hypothesized that we would detect legacy effects of the cover crops planted in year 1 of a 3-yr crop sequence on the arthropod community in the subsequent 2 yrs, and that these effects would be influenced by the intensity of tillage. We compared four systems in a factorial combination of perennial sod and legumes or annual cereal grain and legume as initial cover crops and moldboard or chisel plow tillage implemented in soybeans followed by maize in the subsequent 2 yrs. The entire experiment was initiated twice in adjacent locations, starting in 2003 (Start 1) and 2004 (Start 2). We quantified soil arthropod activity-density and community composition and identified all arthropods to order or family, and the ground and tiger beetles (Coleoptera: Carabidae) to species. In Start 1, but not Start 2, arthropod activity-density increased with each year following implementation of organic management. We observed few legacy effects of cover crop or tillage intensity on arthropod activity-density. The composition of the soil arthropod community was primarily defined by the initial cover crop in the first year, and by the interaction between cover crop and tillage intensity in the second and third year. A legacy effect associated with a yr-1 cover crop of cereal rye was observed for Scarabaeidae beetles and Formicidae (ants) in yr 2 and Carabidae beetles in yr 3 of Start 1, but not Start 2. Weed indicators contributed significantly to the variation in the soil arthropod community that was explained by the environment in yr 2 in Start 1, and in yr 3 in both Starts. Our observations support the concept that both immediate and legacy effects of management shape arthropod communities during the organic transition period, suggesting that transitioning systems could be managed in ways that conserve or enhance natural enemy populations.

Temporal variations of ground-dwelling arthropods in relation to grassland salinization

The richness and abundance of ground-dwelling arthropods were investigated by a space-for-time substitution approach from spring to autumn of 2012 in the Hexi Corridor region, Gansu Province, to understand the effects of grassland salinization on the temporal distribution of the ground-dwelling arthropod community. The results showed that: 1) grassland salinization had a serious damage to the ground-dwelling arthropod community. The magnitude of the decrease was spring > summer > autumn, resulting in obvious change on seasonal distribution pattern of the ground-dwelling arthropod community; 2) the abundance of predators, herbivores and decomposers decreased significantly in all three seasons with salinization development, with greater effects in spring than in summer and autumn; 3) with salinization development, the most abundant taxon was Formicidae. However, the second dominant family changed over the time of the study. For example, in the lightly salinized grassland, the second dominant families were Lycosidae in spring and autumn, they were gradually replaced by Tenebrionidae in spring and Gnaphosidae in autumn in the severely salinized grassland; and 4) changes in the ground-dwelling arthropod community were largely related to changes in the physical environment and resource availability during the process of grassland salinization. Our results suggest that plant density, vegetation cover and fine particles content played important roles in structuring the ground-dwelling arthropods during the process of grassland salinization.

Density-Dependent Effects of an Invasive Ant on a Ground-Dwelling Arthropod Community.

It is frequently assumed that an invasive species that is ecologically or economically damaging in one region, will typically be so in other environments. The Argentine ant Linepithema humile (Mayr) is listed among the world's worst invaders. It commonly displaces resident ant species where it occurs at high population densities, and may also reduce densities of other ground-dwelling arthropods. We investigated the effect of varying Argentine ant abundance on resident ant and nonant arthropod species richness and abundance in seven cities across its range in New Zealand. Pitfall traps were used to compare an invaded and uninvaded site in each city. Invaded sites were selected based on natural varying abundance of Argentine ant populations. Argentine ant density had a significant negative effect on epigaeic ant abundance and species richness, but hypogaeic ant abundance and species richness was unaffected. We observed a significant decrease in Diplopoda abundance with increasing Argentine ant abundance, while Coleoptera abundance increased. The effect on Amphipoda and Isopoda depended strongly on climate. The severity of the impact on negatively affected taxa was reduced in areas where Argentine ant densities were low. Surprisingly, Argentine ants had no effect on the abundance of the other arthropod taxa examined. Morphospecies richness for all nonant arthropod taxa was unaffected by Argentine ant abundance. Species that are established as invasive in one location therefore cannot be assumed to be invasive in other locations based on presence alone. Appropriate management decisions should reflect this knowledge.

Does fire affect the ground-dwelling arthropod community through changes to fine-scale resource patches?

In semiarid ecosystems, perennial trees create resource patches beneath their canopies by providing shade and accumulating litter. These patches are often distinctly different from inter-tree areas, which support scattered hummock grasses. Although patchiness is regarded as an important driver of faunal diversity, it is not known how it is affected by disturbances such as fire. In this study, we tested how resource patches and fire affect the ground-dwelling arthropod community. We sampled ground-dwelling arthropods under the canopy of mallee (Eucalyptus trees), and in adjacent open areas in: (1) an area burnt over 30 years ago (‘long unburnt’), and (2) an area burnt 4 years ago (recently burnt). Five taxa (cockroaches, isopods, spiders, jumping spiders and wasps) were more abundant under the canopy than in the open across both burn treatments, whereas ants showed the opposite pattern. Irrespective of patch type, silverfish, wasps and isopods were more abundant in the long-unburnt stand than the recently burnt stand. Ants showed the opposite pattern. Both long unburnt and recently burnt stands supported a similar abundance of beetles, cockroaches and spiders. Our results demonstrate that many arthropod taxa are affected by the resources provided by trees (litter, shade), even in areas recently burnt by fire. This is likely to change over time and in relation to further disturbance.

Ground-dwelling arthropod community response to native grassland conversion in a temperate desert of northwestern China

Oases are common in desert regions of northwestern China and are major sites for human settlement. The implementation of oasis conservation planning has led to afforestation with appropriate shrubs and trees in the native grasslands surrounding inhabited oases. However, little is known about how this Land use change from native grassland to shrub and tree plantations influences the composition of ground-dwelling arthropod communities and the performance of their different trophic groups. To address this, we measured activity density, taxon richness, and relative abundance of four different ground arthropod trophic groups (spiders, beetle predators, beetle herbivores, and beetle detritivores) and several environmental variables affecting arthropod distributions (vegetation cover, ground temperature, soil moisture, soil properties, and leaf litter) along an experimentally established land use change gradient of a mature shrub (Haloxylon ammodendron) planation, a mature poplar (Populus gansuensis) plantation and a mature pine (Pinus sylvestris) plantation, as well as a native grassland from which all cultivated systems were converted. We found that converted shrub plantation had much lower activity density of predatory, herbivorous, and detritivorous beetles; similar activity density of spiders; and similar taxa richness of all four trophic groups relative to the native grassland. However, converted forest plantations regardless of tree species had much higher activity density of spiders, lower activity density of the three beetle groups, much higher richness of predatory beetles, and lower richness of herbivorous and detritivorous beetles. We also found a change in the composition of the ground arthropod community that was largely driven by changes in ground temperature and leaf litter mass. We conclude that conversion of native grassland to shrub and tree plantations can significantly affect ground-dwelling arthropod communities, reducing the activity of ground-dwelling beetle assemblages while increasing that of ground-dwelling spider assemblages. These findings are important for conserving native arthropod diversity in desert ecosystems.